The present invention relates to an electronic device system for allowing component electronic devices to exchange data therebetween through a data interface pursuant to a predetermined data communication format; to electronic devices constituting such an electronic device system; and to a synchronized power supply controlling method for synchronously controlling power supply status of a plurality of electronic devices making up an electronic device system.
Today, the IEEE (Institute of Electrical and Electronic Engineers) 1394 data interface has gained widespread acceptance as a digital data interface. Faster than the SCSI (Small Computer System Interface) among others in terms of data transfer rates, the IEEE 1394 data interface is known to permit isochronous communication whereby data of a predetermined size are transmitted and received periodically. As such, the IEEE 1394 data interface is deemed advantageous in transferring stream data such as AV (audio/video) data in real time.
Under these circumstances, those AV systems have been proposed which interconnect various digital AV devices and electronic equipment such as a personal computer via a data bus complying with data interface standards such as the IEEE 1394.
Conventional AV systems have their component devices switched on and off in a synchronized manner as follows:
Common AV systems popularly known as audio component systems are constituted by combining diverse components (such as music source recording/reproducing apparatus, amplifiers, etc.) into a single integrated piece of audio equipment. When a main power supply of such an audio component system is turned on or off, the components making up the system are turned on or off synchronously through the use of, say, a local internal bus installed for control purposes.
It has been common practice over the years to plug an AV device into a synchronously operated power outlet furnished on an amplifier or like equipment constituting an audio component system. In that setup, the configured devices are turned on and off in synchronism with the amplifier being switched on and off.
Data interface standards such as the IEEE 1394 permit in principle intercommunication between devices regardless of their different venders as long as they share, say, an IEEE 1394 interface function. That is, component devices making up a system through their IEEE 1394 data interfaces are each recognized as an independent unit attached to a data bus of the system.
The individual devices are each powered independently from a commercial AC source. This means that a system, when configured, may or may not have its component devices turned on and off in an interconnected manner using synchronously controlled power sources.
An AV system may be built on an IEEE 1394 data interface interconnecting devices of the same series or specific models from the same vender with a view to implementing functions of a typical audio component system. In that case, the component devices are currently recognized as an independent device each on a common data bus and thus will not be turned on or off synchronously. In view of improving the ease of operation and the convenience of usage, it is obviously desirable for such an AV system to have its components powered on and off in an interconnected manner.
Some conventional audio component systems are known to have their component devices switched on and off in synchronism with power supply status of an amplifier or like device that functions as the core of the system. On the other hand, there has yet to be developed a function allowing the principal device of a system to be controlled in power supply status in synchronized relation with any other component device being switched on and off. In other words, no function has so far been implemented whereby a controlling device of a system would be controlled in power supply status by any one of controlled devices making up the system.
Any system built on an IEEE 1394 data bus structure, it should be noted, is not fixed in its signal flow by physical cable connections. The configured devices attached to the data bus are allowed in principle to communicate with one another in the system, so that each of the component audio devices may be controlled in diverse ways. Such a setup may thus be supplemented by a function for letting the principal device be controlled effectively in power supply status by any one of the other configured devices in the system.
The present invention has been made in view of the above circumstances and according to one aspect of the invention, there is provided an electronic device system constituted by a source output device and a controlling device interconnected via a data bus complying with a predetermined communication format, the source output device transmitting a source signal and a response command over the data bus, the controlling device receiving the source signal over the data bus and transmitting a query command to the source output device, the source output device and the controlling device having an independent power supply input each, the electronic device system comprising: a transmitting element for causing the controlling device to transmit to the source output device, over the data bus, the query command querying whether the source output device is switched off; a receiving element for receiving the response command from the source output device; a judging element for judging whether the response command received by the receiving element indicates that the source output device is switched off; and a controlling element which, if the response command received by the receiving element is judged by the judging element to indicate that the source output device is switched off, then switches off the controlling device.
According to another aspect of the invention, there is provided a controlling device which has an independent power supply input and which is connected to a source output device with an independent power supply input by means of a data bus complying with a predetermined communication format, the controlling device comprising: a receiving element for receiving a source signal and a response command from the source output device over the data bus; a transmitting element for transmitting a query command to the source output device over the data bus, the query command querying whether the source output device is switched off; a judging element for judging whether the response command received by the receiving element indicates that the source output device is switched off; and a controlling element which, if the response command judged by the judging element indicates that the source output device is switched off, then turns off the controlling device.
Other objects, features and advantages of the invention will become more apparent upon a reading of the following description and appended drawings.